In the papermaking art, an aqueous suspension containing cellulosic fibres, and optionally fillers and additives, referred to as stock, is fed into a headbox which eje cts the stock onto a forming wire. Water is drained from the stock through the forming wire, so that a wet web of paper is formed and dewatered on the wire. The paper web is then dried in the drying section of the paper machine. Drainage and retention aids are conventionally introduced into the stock in order to facilitate drainage and to increase adsorption of fine particles onto the cellulosic fibres to retain them with the fibres on the wire.
U.S. Pat. No. 4,388,150 discloses a binder in papermaking comprising a complex of cationic starch and colloidal silicic acid to produce a paper having increased strength and improved levels of retention of added minerals and papermaking fines.
U.S. Pat. No. 4,750,974 discloses a coarcervate binder for use in papermaking comprising a tertiary combination of a cationic starch, an anionic high molecular weight polymer and a dispersed silica.
U.S. Pat. No. 5,368,833 discloses silica sols containing aluminium modified silica particles with high specific surface area and a high content of microgel.
U.S. Pat. No. 6,083,997 discloses anionic nano-composites, which are prepared by adding a polyelectrolyte to silicate solution and then combining them with silicic acid. The nano-composites exhibit retention and drainage performance in papermaking.
EP 0 418 015 A1 discloses an active sizing composition containing an aqueous emulsion in combination with an anionic dispersant or emulsifier. By using anionic polyacrylamide, anionic starch or colloidal silica the anionic charge density in the sizing composition can be extended.
U.S. Pat. No. 4,443,496 refers to a method for modifying a surface layer of handened cement or substrates with use of the agent which comprises in a specified ratio of an alkali silicate solution and a sodium naphthalene sulphonate formaldehyde condensate.
U.S. Pat. No. 4,559,241 relates to an aqueous solution of alkali metal silicate and nitrite. The solution may also contain additives such as formaldehyde condensate with naphthalene sulphonate.
U.S. Pat. No. 5,595,629 refers to a papermaking process comprising adding to the slurry an anionic polymer and cationic polymer in order to increase retention and/or dewatering. The anionic polymer comprises a formaldehyde condensate of naphthalene sulfonic acid salt with a molecular weight range of 500 to 120,000.
U.S. Pat. No. 6,033,524 discloses a method for increasing retention and drainage of filling components in a paper making furnish in a paper making process comprising adding to the furnish a slurry of filling components, also containing a phenolic enhancer.
U.S. Pat. No. 4,772,332 pertains to a heat stabilised slurry of bulked kaolin pigment which is prepared by mixing a water soluble cationic material with kaolin clay pigment in the presence of water.
U.S. Pat. No. 5,733,414 relates to a process for manufacturing paper from a cellulosic suspension comprising adding a water soluble cationic polymer and a water soluble formaldehyde condensate resin.
U.S. Pat. No. 5,110,414 discloses a procedure for manufacturing lignocellulosic material products and improving their strength and water resistant characteristics, high molar mass lignin derivatives being added to the material.
It would be advantageous to be able to provide drainage and retention aids with improved performance. It would also be advantageous to be able to provide retention and drainage aids with good storag e stability. It would further be advantageous to be able to provide a papermaking process with improved drainage and/or retention performance.